SBIG ST-2000XCM Color CCD Camera

Like their monochrome counterparts, the ST-2000XCM and ST-2000XCMI cameras are the same, except that the ST-2000XCMI does not have the built-in TC-237H tracking CCD and some of the accessories that are included with the ST-2000XCM (see the comparison table below). In March of 2006 we added the Remote Guide Head Port to both the single sensor ST-2000XMI and dual sensor ST-2000XM cameras. Both versions use a high quality interline CCD from Kodak, the KODAK DIGITAL SCIENCE KAI-2020CM Image Sensor Megapixel Progressive Scan Interline CCD.

The KODAK DIGITAL SCIENCE KAI-2020CM is a high-performance multi-megapixel image sensor designed for a wide range of scientific, medical imaging, and machine vision applications. The 7.4 mm square pixels with microlenses provide high sensitivity and the large full well capacity results in high dynamic range. The vertical overflow drain structure provides antiblooming protection, and enables electronic shuttering for precise exposure control to 0.001 seconds. Other features include low dark current, negligible lag and low smear. The KAI-2020CM CCD is a 2 megapixel progressive scan detector with an active image area of 1.92 million pixels. The active image area is 1600 x 1200 pixels. This array is 75% larger than the Sony CCD used in competitors' "one-shot color megapixel" cameras, nearly as large as an ST-8XME, and the ST-2000XM is a self-guiding camera, utilizing SBIG's patented dual sensor design. Although the imaging CCD is nearly the same size as the KAF-1602E used in the ST-8XME, due to the smaller pixel size it contains nearly half a million more pixels than the ST-8XME.

The latest KAI-2020CM 2 megapixel CCD has all of the same improvements as the monochrome KAI-2020M: a high gain output amplifier that reduces the read noise by almost half compared to the previous CCD, 10X fewer bright points, and lower dark current. The ST-2000XCM also has the larger 657x495 pixel TC-237H built-in guiding CCD instead of the TC-211. This improvement was the same as the upgraded autoguider installed on the larger ST-8XE, ST-9XE and ST-10XE cameras.

In May of 2004 SBIG began including a custom Pelican carrying and storage case with the ST-2000XM and ST-2000XCM models. This case is dustproof, waterproof and crushproof and carries a lifetime guarantee from Pelican. As of the date of this announcement, we are also upgrading the version of TheSky software by Software Bisque that we include with the ST-2000XCM camera from version 4 to version 5. If you have a Macintosh computer running OS-X we will even throw in Equinox camera control and planetarium software for the Mac as well! A Linux acquisition program is free and other Linux software is also available. We continue to include CCDSoftV5 in addition to CCDOPS version 5 the most complete package of camera control, image processing, astrometric, star charting and planetarium software available with any new CCD camera from any manufacturer. Upgrades are available for most of these improvements for older ST-2000XM camera owners. All of these improvements have come at no additional increase in the price of the ST-2000XCM camera.

The full frame download time is approximately 4.5 seconds with our high speed USB electronics. This camera is also fully compatible with all of our existing accessories such as the CFW8 filter wheel and AO-7 adaptive optics device. Because the ST-2000XCM has two CCDs (a guiding CCD as well as an imaging CCD) in the same camera head, it is capable of self-guiding without any compromise in the quantum efficiency of the imaging CCD. In other words, not only CAN it self-guide, it can do so without having to double the exposure time to compensate for the guiding feature.

The following are some common questions and answers about this new color camera:

Q1. What is the pixel size and array size?

A1. Same as the ST-2000XM monochrome CCD: 1600 x 1200 pixels at 7.4 microns square.

Q2. Is there any loss of resolution compared to imaging with a monochrome ST-2000XM?

A2. Yes and no. If by resolution you mean the total number of pixels used to make up the final image, then no, there is no loss. Color images will be 1600 x 1200 pixels, just like monochrome images from an ST-2000XM camera. However, if by resolution you mean the ability to resolve detail, then there is a possible loss of detail compared to imaging through external filters using a monochrome CCD where each pixel of the CCD is exposed to each colored filter and then merged to create a color image. In the case of the color CCD, since each pixel sees only one color, the RG and B values for each pixel must be created from the data available from the remaining pixels. This data is gathered from neighboring pixels during the merge The final image is therefore a full 1600 x 1200 but each pixel contains data that has been interpolated from neighboring pixels to create a color file.

To think of it another way - imagine imaging an object that is entirely one color, such as an H-alpha nebula. The raw full frame grayscale image will appear bright every 4th pixel (red) and dark in the others (blue and green) until you perform a color merge to create an RGB image. Then the non-red pixels are interpolated and the full 1600 x 1200 pixels compose the final image.

Q3. What is the size of the guide chip?

A3. The guide chip is the TC-237H with 657 x 495 pixels at 7.4 microns square.

Q4. Since the color imaging is done without a filter wheel, will it be easier for locate guide stars?

A4. Yes. Since the imaging CCD has the filters directly over the array, the guide chip will always be using the full spectrum to view guide stars.

Q5. Can the color data be separately processed like current RGB files before combining?

A5. Yes, our software will allow you to extract separate R, G and B files from the original frame which you can process separately just as you would with separate RGB files from a monochrome CCD.

Q6. Can you color combine automatically without processing the separate files first?

A6. Yes. We plan to add a feature to CCDOPS where the image will be automatically merged as it is displayed. So when you take an image and look at it on the computer monitor it will be in color.

Q7. How does the camera's QE compare to the monochrome ST-2000XM?

A7. The monochrome version has higher QE without filters and still somewhat higher QE with our dichroic filters. When you take into account the transmission of the RGB filters and the native QE of the CCD, then the filtered monochrome CCD and the color CCD are very similar. Our dichroic filters are better than the micro-filters so there is still a benefit in QE (as well as resolution) to using an external filter wheel. The price is longer overall exposure time. The chart below shows the QE of a KAI-2001M CCD, the effective QE of the KAI-2001M monochrome CCD when external filters are added and the filtered QE for the KAI-2001CM color CCD from the Kodak data sheet.

Q8. Can narrow band filters such as H-alpha filters be used with a color CCD?

A8. Yes. However, for narrow band imaging a monochrome CCD is better because each pixel sees the filtered signal. But binning the color CCD 2x2 and using it as a monochrome narrow band imager is possible albeit with somewhat lower sensitivity than the monochrome version.

The ST-2000XCM is a complete camera system. There is no need to add in the additional cost of an interface or an autoguider or a nosepiece or better software to make these cameras actually operate as they should. Everything that is needed to make the camera operational is included in the base price. We even include some non-essential, but desirable, items such as a custom hard carrying case.

Complete Systems

Each new ST-2000XM camera system INCLUDES at no additional cost: